1. Field of the Invention
The present invention is directed to a method for producing a print image on a carrier material, whereby ink-attracting and ink-repelling areas are produced on a surface of a print medium according to the structure of the print image to be printed, whereby the ink-repellant areas are provided with a layer of an ink-repellant medium, ink is applied onto the surface, this adhering to the ink-attracting areas and not being picked up by the ink-repellant areas, and whereby the ink distributed on the surface is printed onto the carrier material.
The invention is also directed to an apparatus for producing a print image on a carrier material.
2. Description of the Related Art
Given a known offset printing process which works without water, the areas not to be printed are fat-repellant, they do not accept any ink. The areas to be printed, by contrast, are fat-attracting and can accept fat-containing ink. The ink-attracting and ink-repellant areas are distributed on a printing plate such that they reproduce the print image to be printed. The printing plate can be employed for a plurality of transfer printing events. A new printing plate with ink-attracting and ink-repellant areas must be produced for each print image.
Given the known direct imaging method of Heidelberger Druckmaschinen, a print master is produced in the printing system on a silicone-coated film by partially burning the silicone layer off. The silicone-free locations form the color-attracting areas and can pick color up during the printing process.
In another offset process working with water, hydrophobic and hydrophilic areas corresponding to the structure of the print image to be printed are produced on the print medium. Before applying ink to the print carrier, a thin moisture film is first applied onto the print carrier by employing application rollers or, respectively, sprayer devices, this wetting the hydrophilic area of the print carrier. With the assistance of an inking roller, ink is subsequently applied onto the surface of the print carrier; this, however, moistens only the areas not covered with the moisture film. After the inking of the print carrier, the ink print image is finally transferred onto the carrier material.
A method developed by Oce Printing Systems GmbH is also known wherein hydrophobic and hydrophilic areas are formed on the surface of the print carrier. The hydrophilic areas are moistened, so that no ink adheres to them. The surface of the print carrier is charged with water steam for moistening. The charging with water steam can also ensue such that hydrophilic areas arise corresponding to the structures of the print image to be printed. The ink is only picked up by areas that have not been provided with a moisture film. The aforementioned methods have the problem that the ink-water equilibrium must be very narrowly toleranced in order to achieve a high printing quality.
British patent document GB-A-1208731 discloses a method or, respectively, an apparatus for producing a print image on a carrier material. A substance in its solid phase is applied on a surface of a carrier material. This substance is heat sensitive and can be structured according to predetermined picture elements under the influence of heat, whereby this solid substance is removed. The uncovered surface of the print carrier can be brought into a hydrophilic condition. When inking with ink particles containing water, these adhere to the hydrophilic areas, whereas the hydrophobic areas of the substance in its solid phase repel these ink particles.
U.S. Pat. No. 3,741,118 discloses a method and an apparatus for printing an image, whereby a technique is utilized that approximately corresponds to a standard lithography technique. Upon application of electronic scanning technology, ink is selectively applied on a plate or an existing layer is selectively removed. The ink on the plate is then transferred onto paper. Subsequently, the plate is cleaned and can be prepared anew for the acceptance of ink.